我們來復(fù)習(xí)一下小數(shù)點(diǎn)搬家吧市公開課金獎(jiǎng)市賽課一等獎(jiǎng)?wù)n件

我們來復(fù)習(xí)一下小數(shù)點(diǎn)遷居吧！小數(shù)點(diǎn)向右移動(dòng)（）位，這個(gè)數(shù)就擴(kuò)大（）倍。反過來：一個(gè)數(shù)擴(kuò)大（）倍，只要把它小數(shù)點(diǎn)往（）邊移動(dòng)（）位就能夠了。

第1頁第1頁小數(shù)點(diǎn)向左移動(dòng)（）位，這個(gè)數(shù)就縮?。ǎ┍丁７催^來：一個(gè)數(shù)縮?。ǎ┍叮灰阉?shù)點(diǎn)往（）邊移動(dòng)（）位就能夠了。

第2頁第2頁由此可見，一個(gè)數(shù)擴(kuò)大或縮小10倍、100倍、1000倍……，只要相應(yīng)地把這個(gè)數(shù)小數(shù)點(diǎn)往右或往左移動(dòng)一位、兩位、三位……就能夠了。第3頁第3頁你能通過移動(dòng)小數(shù)點(diǎn)辦法直接寫出得數(shù)嗎？15×10=1.3×10=0.01×10=3×100=1.3×100=0.04×100=0.5×1000=4.1×1000=6×1000=第4頁第4頁你能通過移動(dòng)小數(shù)點(diǎn)辦法直接寫出得數(shù)嗎？12÷10=4.3÷10=0.1÷10=3÷100=1.3÷100=0.04÷100=5÷1000=0.11÷1000=0.2÷1000=第5頁第5頁同窗們，你們還記得乘數(shù)與積改變規(guī)律嗎？一個(gè)乘數(shù)擴(kuò)大10倍，另一個(gè)乘數(shù)擴(kuò)大100倍，那么積擴(kuò)大（）倍。一個(gè)乘數(shù)擴(kuò)大1000倍，另一個(gè)乘數(shù)擴(kuò)大10倍，那么積擴(kuò)大（）倍。一個(gè)乘數(shù)縮小10倍，另一個(gè)乘數(shù)也縮小10倍，那么積縮?。ǎ┍丁Ｒ粋€(gè)乘數(shù)縮小100倍，另一個(gè)乘數(shù)縮小10倍，那么積縮?。ǎ┍?。第6頁第6頁算式第一個(gè)乘數(shù)小數(shù)數(shù)位第二個(gè)乘數(shù)小數(shù)數(shù)位積小數(shù)數(shù)位2×0.4=0.2×0.4=0.12×3=0.12×0.3=第7頁第7頁算式第一個(gè)乘數(shù)小數(shù)數(shù)位第二個(gè)乘數(shù)小數(shù)數(shù)位積小數(shù)數(shù)位2×0.4=0.80110.2×0.4=0.12×3=0.12×0.3=第8頁第8頁算式第一個(gè)乘數(shù)小數(shù)數(shù)位第二個(gè)乘數(shù)小數(shù)數(shù)位積小數(shù)數(shù)位2×0.4=0.80110.2×0.4=0.081120.12×3=0.12×0.3=第9頁第9頁算式第一個(gè)乘數(shù)小數(shù)數(shù)位第二個(gè)乘數(shù)小數(shù)數(shù)位積小數(shù)數(shù)位2×0.4=0.80110.2×0.4=0.081120.12×3=0.362020.12×0.3=第10頁第10頁算式第一個(gè)乘數(shù)小數(shù)數(shù)位第二個(gè)乘數(shù)小數(shù)數(shù)位積小數(shù)數(shù)位2×0.4=0.80110.2×0.4=0.081120.12×3=0.362020.12×0.3=0.036213第11頁第11頁小數(shù)乘小數(shù)，能夠先把它們看作整數(shù)來乘，然后看這兩個(gè)小數(shù)小數(shù)部分一共有幾位小數(shù)，它們積就是幾位小數(shù)。第12頁第12頁算一算，我看你準(zhǔn)行！請(qǐng)你依據(jù)乘數(shù)小數(shù)位數(shù)與積小數(shù)位數(shù)關(guān)系直接寫出得數(shù)

0.5×0.1=0.3×0.2=0.01×0.4=0.15×0.2=2.5×0.4=3.2×0.01=0.04×0.4=0.5×0.01=1.2×10=4.3×100=0.1×0.1=0.03×0.11=1.3×0.002=0.04×10=0.5×0.4=0.01×0.6=

第13頁第13頁算一算，我看你準(zhǔn)行！請(qǐng)你依據(jù)乘數(shù)小數(shù)位數(shù)與積小數(shù)位數(shù)關(guān)系直接寫出得數(shù)

0.5×0.1=0.050.3×0.2=0.060.01×0.4=0.15×0.2=2.5×0.4=3.2×0.01=0.04×0.4=0.5×0.01=1.2×10=4.3×100=0.1×0.1=0.03×0.11=1.3×0.002=0.04×10=0.5×0.4=0.01×0.6=

第14頁第14頁算一算，我看你準(zhǔn)行！請(qǐng)你依據(jù)乘數(shù)小數(shù)位數(shù)與積小數(shù)位數(shù)關(guān)系直接寫出得數(shù)

0.5×0.1=0.050.3×0.2=0.060.01×0.4=0.0040.15×0.2=0.032.5×0.4=3.2×0.01=0.04×0.4=0.5×0.01=1.2×10=4.3×100=0.1×0.1=0.03×0.11=1.3×0.002=0.04×10=0.5×0.4=0.01×0.6=

第15頁第15頁算一算，我看你準(zhǔn)行！請(qǐng)你依據(jù)乘數(shù)小數(shù)位數(shù)與積小數(shù)位數(shù)關(guān)系直接寫出得數(shù)

0.5×0.1=0.050.3×0.2=0.060.01×0.4=0.0040.15×0.2=0.032.5×0.4=13.2×0.01=0.0320.04×0.4=0.5×0.01=1.2×10=4.3×100=0.1×0.1=0.03×0.11=1.3×0.002=0.04×10=0.5×0.4=0.01×0.6=

第16頁第16頁算一算，我看你準(zhǔn)行！請(qǐng)你依據(jù)乘數(shù)小數(shù)位數(shù)與積小數(shù)位數(shù)關(guān)系直接寫出得數(shù)

0.5×0.1=0.050.3×0.2=0.060.01×0.4=0.0040.15×0.2=0.032.5×0.4=13.2×0.01=0.0320.04×0.4=0.0160.5×0.01=0.0051.2×10=4.3×100=0.1×0.1=0.03×0.11=1.3×0.002=0.04×10=0.5×0.4=0.01×0.6=

第17頁第17頁算一算，我看你準(zhǔn)行！請(qǐng)你依據(jù)乘數(shù)小數(shù)位數(shù)與積小數(shù)位數(shù)關(guān)系直接寫出得數(shù)

0.5×0.1=0.050.3×0.2=0.060.01×0.4=0.0040.15×0.2=0.032.5×0.4=13.2×0.01=0.0320.04×0.4=0.0160.5×0.01=0.0051.2×10=124.3×100=4300.1×0.1=0.03×0.11=1.3×0.002=0.04×10=0.5×0.4=0.01×0.6=

第18頁第18頁算一算，我看你準(zhǔn)行！請(qǐng)你依據(jù)乘數(shù)小數(shù)位數(shù)與積小數(shù)位數(shù)關(guān)系直接寫出得數(shù)

0.5×0.1=0.050.3×0.2=0.060.01×0.4=0.0040.15×0.2=0.032.5×0.4=13.2×0.01=0.0320.04×0.4=0.0160.5×0.01=0.0051.2×10=124.3×100=4300.1×0.1=0.010.03×0.11=0.00331.3×0.002=0.04×10=0.5×0.4=0.01×0.6=

第19頁第19頁算一算，我看你準(zhǔn)行！請(qǐng)你依據(jù)乘數(shù)小數(shù)位數(shù)與積小數(shù)位數(shù)關(guān)系直接寫出得數(shù)

0.5×0.1=0.050.3×0.2=0.060.01×0.4=0.0040.15×0.2=0.032.5×0.4=13.2×0.01=0.0320.04×0.4=0.0160.5×0.01=0.0051.2×10=124.3×100=4300.1×0.1=0.010.03×0.11=0.00331.3×0.002=0.00260.04×10=0.40.5×0.4=0.01×0.6=

第20頁第20頁算一算，我看你準(zhǔn)行！請(qǐng)你依據(jù)乘數(shù)小數(shù)位數(shù)與積小數(shù)位數(shù)關(guān)系直接寫出得數(shù)

0.5×0.1=0.050.3×0.2=0.060.01×0.4=0.0040.15×0.2=0.032.5×0.4=13.2×0.01=0.0320.04×0.4=0.0160.5×0.01=0.0051.2×10=124.3×100=4300.1×0.1=0.010.03×0.11=0.00331.3×0.002=0.00260.04×10=0.40.5×0.4=0.20.01×0.6=0.006

第21頁第21頁已知12.3×0.14=1.722你能不久說出括號(hào)里數(shù)是多少嗎？（）×14=1.722（）×1.4=1.722（）×0.014=1.7220.123×（）=1.722123×（）=1.722第22頁第22頁已知12.3×0.14=1.722你能不久說出括號(hào)里數(shù)是多少嗎？（0.123）×14=1.722（）×1.4=1.722（）×0.014=1.7220.123×（）=1.722123×（）=1.722第23頁第23頁已知12.3×0.14=1.722你能不久說出括號(hào)里數(shù)是多少嗎？（0.123）×14=1.722（1.23）×1.4=1.722（）×0.014=1.7220.123×（）=1.722123×（）=1.722第24頁第24頁已知12.3×0.14=1.722你能不久說出括號(hào)里數(shù)是多少嗎？（0.123）×14=1.722（1.23）×1.4=1.722（123）×0.014=1.7220.123×（）=1.722123×（）=1.722第25頁第25頁已知12.3×0.14=1.722你能不久說出括號(hào)里數(shù)是多少嗎？（0.123）×14=1.722（1.23）×1.4=1.722（123）×0.014=1.7220.123×（14）=1.722123×（）=1.722第26頁第26頁已知12.3×0.14=1.722你能不久說出括號(hào)里數(shù)是多少嗎？（0.123）×14=1.722（1.23）×1.4=1.722（123）×0.014=1.7220.123×（14）=1.722123×（0.014）=1.722第27頁第27頁再來算一算，我看你準(zhǔn)行！請(qǐng)你依據(jù)乘數(shù)小數(shù)位數(shù)與積小數(shù)位數(shù)關(guān)系直接寫出得數(shù)

0.4×0.2=0.3×0.3=0.01×0.4=0.05×0.2=0.5×0.4=3.2×0.01=0.04×0.6=0.5×0.05=1.2×10=4.3×100=0.1×0.01=0.03×0.21=1.3×0.02=0.04×100=0.05×0.4=0.01×0.6=第28頁第28頁下列小數(shù)去掉小數(shù)點(diǎn)后是多少？2.6（）0.8（）0.012（）61.04（）0.15（）0.201（）第29頁第29頁用豎式計(jì)算1.2×0.02=2.6×0.8=2.15×0.12=0